On 21 February 2020, the first person-to-person transmission of SARS-CoV-2 – the virus responsible for Covid-19 – was reported in Italy. After that, the number of people infected with Covid-19 increased rapidly, first in northern regions and then in all Italian territories.

On 21 February 2020, the first person-to-person transmission of SARS-CoV-2 – the virus responsible for Covid-19 – was reported in Italy. After that, the number of people infected with Covid-19 increased rapidly, first in northern regions and then in all Italian territories.

Covid-19 is a highly contagious infectious disease caused by the newly emerged virus, SARS-CoV-2. The virus rapidly spread and was declared a pandemic by the World Health Organization on 11 March 2020. By 26 May 2020, worldwide confirmed cases reached 5,543,439 with 347,836 deaths.1

This article explores what people mean when they talk about testing for Covid-19 and how we should interpret test results. There are two main types of tests: those that detect active infection, and those that test past infection.1

This article explores what people mean when they talk about testing for Covid-19 and how we should interpret test results. There are two main types of tests: those that detect active infection, and those that test past infection.1